The present invention relates to a control device for controlling the cyclic and collective pitch of a helicopter rotor.
In known helicopter rotors the cyclic and collective pitches are normally controlled by means of an oscillating plate control device including two concentric rings the outer of which is rotatably supported by the inner and is drivingly connected to a drive shaft to carry into rotation the pitch changing rods each pivoted in an eccentric position to an associated blade.
In the above described known rotors the side inner ring is mounted on a ball-joint through which the drive shaft passes and which is supported by a pylon which is angularly fixed and axially movable, and can oscillate about the centre of the said ball-joint under the thrust of a plurality of fixed fluid pressure actuators uniformly distributed about the drive shaft.
The known cyclic and collective pitch control device described above has, in general, various disadvantages deriving both from the complexity of its component parts and from the extremely high precision required correctly to couple these together, and from the high rigidity conferred on the whole oscillating plate by the direct coupling between the fixed ring thereof and the said fixed pylon.